1. The Field of the Invention
The invention relates to a glass ceramic or glass element that can be subjected to high thermal loads and is decorated with a metallic color based on melted silicate to which effect pigments have been added.
2. Related Art
Such colorants based on a silicate melt are typically ceramic colorants with molten glass as a base. They are baked onto the substrate at a high temperature.
When so-called effect pigments, special metal effect or pearlescent pigments are used as the pigments, the corresponding metallic colors can be prepared. Various pearlescent pigments comprising mica platelets coated with inorganic oxides, such as TiO2, SnO2 and Fe2O3, are commercially available, for example, under the name IRIODIN® (Merck).
Glass ceramics or glass elements decorated with the aforesaid metallic colors are made, in particular, as glass ceramic plates or plates consisting of tempered special glass with a low thermal expansion coefficient, such as borosilicate glass, and are used typically for cooking surfaces in cooking areas, namely for applications in which the plates are subjected to high thermal loads. However, fireplace sight glasses, baking oven sight glasses and lamp covers made of these materials, for example, are also increasingly being decorated with the aforesaid colors.
Because, in particular, cooking surfaces in cooking areas of modern kitchens are conspicuous because of their large surface area and decisively influence the design which is markedly customer-dependent and differs from country to country, the most varied decorations are described in numerous publications. They range from simple patterns, for example company logos or cooking area markings, to complex full-surface decorations. Important besides the design is, in particular, the protection against surface scratches and the reduction in susceptibility to soiling, for example to finger prints and metal particles produced by abrasion as well as to marks resulting from use. Such decorations and their application to a glass ceramic plate are described, for example, in DE 44 26 234 C1 (=EP 0 693 464 B1) and DE 34 33 880 C2. Other decorated cooking surfaces are disclosed in DE 197 28 881 C1 (=DE 297 11 916 U1), DE 100 14 373 C2 and DE 200 19 210 U1. The last two publications also describe decorations with sol-gel-based colorants containing metal effect, pearlescent or interference pigments, namely effect pigments producing a metallic effect in the color. Such molten glass-based colorants, namely ceramic metallic colorants containing such pigments are also known from the prior art.
In certain market segments, and especially for adaptation to aluminum and stainless steel surfaces in modem kitchens, decorated glass/glass ceramic cooking surfaces with a metallic effect occupy an important position. The previously used effect pigments, however, are not fully satisfactory from the standpoint of the intensity of the metallic effect and the reduction in susceptibility to marks resulting from use.